XXI] MEAT AND MEAT PRODUCTS 285 



and mix thoroughly. Transfer a 20 cc. aliquot of this solution to a 50 cc. meas- 

 uring flask and proceed as directed under 16. Subtract from the combined creati- 

 nin value the equivalent of the pre-formed creatinin, 49, and multiply the difference 

 by 1.16 to convert into creatin. Express the result as per cent of creatin. 



49 CREATININ.-OFFICIAL. 



For creatinin in beef extract measure about 5 cc. of the solution employed in 48 

 into a 500 cc. measuring flask, add 10 cc. of 10% sodium hydroxid solution and 30 

 cc. of the saturated picric acid solution (1.2%), mix and rotate for 30 seconds. Allow- 

 to stand exactly 4^ minutes, then dilute to the mark at once with water. Shake 

 thoroughly and read the depth of color after standing. If the reading is less than 

 7 or over 9.5 mm., repeat, calculating the quantity of solution necessary to obtain a 

 reading of about 8 mm. Express the result as per cent of creatinin, making the 

 calculations as indicated under 16. 



GLYCEROL. 



50 Cook Method^*.— Tentative. 



Weigh 2 grams of a solid or 5 grams of a liquid preparation in a small lead dish or 

 Hofmeister Schalchen containing 20 grams of ignited sand. Transfer the dish and 

 its contents to a mortar containing more ignited sand and several grams of anhydrous 

 sodium sulphate and mix thoroughly. Transfer the mixture, including the dish, 

 to a Soxhlet apparatus which has a piece of cotton placed in the side arm to prevent 

 solid particles from being siphoned over. Extract the entire mass with redistilled 

 anhydrous acetone for 10 hours. Distil the acetone from the extract, carefully re- 

 moving the last trace by means of a vacuum pump. Take up the residue in water, 

 add 5 cc. of 10% silver nitrate solution, make up to a volume of 100 cc, shake, allow 

 to stand overnight, filter and determine glycerol in an aliquot of the filtrate as di- 

 rected under XIX, 6, beginning at the point "Add * * * 30 cc. of the strong 

 potassium dichromate solution". With solid meat and yeast extracts a blank of 

 0.5-1.0 % is obtained in most cases. 



51 SUGAR.-TENTATIVE. 



Heat 20 grams of the sample with about 200 cc. of water on a steam bath until all 

 soluble substances have gone into solution, cool and proceed from this point as 

 directed under 23. Reducing sugar up to 0.5% may be present as a natural con- 

 stituent of meat extracts. 



52 PRESERVAXrVES.-TENTATIVE. 

 Proceed as directed under X. 



53 METALS.— TENTATIVE. 

 Proceed as directed under XII. 



54 NITRATES.-TENTATIVE. 

 Proceed as directed under 26 or 28. 



